This is a simple calculator for conducting a hypothesis test for a single-sample z-test, sigma known. [Note: some authors refer to this as the Large Sample test.]

Important Note: BUS 233 Requirements for using the z-distribution:

- The population standard deviation, sigma (σ), is known.
- The population is normally distributed or the random sample size is greater than or equal to (>=) 30.

**If sigma is known, use the z-test. If sigma is not known, use the t-test** [here].

Note: for large samples, if you do not know the population standard deviation, sigma, use the sample standard deviation, s, in the calculator below.

Enter your data in the blue cells. Then, select the math operator in the Alternative Hypothesis (which tails you the tail of the test) in the orange cell. To get the operator drop-down menu, left-click in the orange cell, e.g. on the current operator.

All the yellow answer cells will be updated accordingly.

If you have wondered why a two-tail p-value for a z-score is always twice the one-value p-value, check out this short read on my TheStatsFiles blog.

Hope this helps.

Dr. Dawn